Method of producing precipitated antimony sulphide



Jue 24 1924.

G. w. MULLEN 'METHOD op PRODUGING PRECIPITATED ANTIMONY suLPHID'E Y* r Filed-Nov. 1'4. 1922 `n n Mon H L "Patented June 24, 1924.

narran stares paraat GEORGE WILBUR MULLEN, OF LMHURST, NEW YORK; ASSIGNOB T0 HOYVBD'B.L I

BISHOP, OF-NEW YORK, N. Y. I

METHOD 0F 'PBOD'UCING PBECHITATED NEEONYSUEEWE.

Application tiled-November 14,' 1922. Serial No. 360,730.

To all lwhom t may concern.'

a citizen of the United States of America,

and a resident of Elmhurst, in the'borough and county of Queens, city and State of New York, have invented certain new and useful improvements in Methods of Producing Preci it-ated Antimony Sulphide, of which the fo lov'ving is a specification.

This invention relates to the production of precipitated antimony sulphide, and has for its object to provide a process which can be carried out economically at a relatively low temperature and which Will yield the product desired under conditions that will preclude losses due to decomposition of the product andI that will accomp-lish the removal of certain undesirable by-products.

Heretofore antimony ore (Stibnite, Sb2S3) has been used as the raW material in the manufacture of precipitated antimony sulphides. l have found that much better results are obtained by starting' with metallic antimony and nitre cake and subjectingv them to my novel treatment, which Will be set forth in detail hereinafter, its `novel features being particularly pointed out in the appended claims.

An apparatus suitable for carrying out my improved method is illustrated by the accompanying drawing, in diagrammatic elevation, with parts in section.

A designates a reverberatory furnace, preferably carrying at its top a container B for the nitre cake, so Vthat the latter may be preheated before being admitted to the interior of said furnace. Hoppers C, D or other suitable means'are provided for feeding to the furnace A the raw antimony material (metallic antimony of commercial purity, that is to say, about 99%) and a reducing agent (coal), respectively. The molten product passes from the outlet of the furnace to a settlerE, generally made as a car, in which the molten material is allowed to cool and solidify, whereupon it is crushed. fit F l have indicated a heap of such crushed material, which is then taken up by an elevator G and dropped into a hopper H which may also receive, as at J, a certain amount'of sulfur in pieces of suitable size to enter the casing K of a disintegrator.

. Thisdisintegrator comprises a perforated cylinder L rotated within the cylindrical casing K and preferably provided on its outer surface with paddles M to agitate the waterwith which said casing is filled'.

Maasai Steam coils or other suitable means (not.

shown) may be provided for heating the disintegrator. A n outlet pipe N for the liquid (with ump, if required) leads to a sludge tank adapted to receive calcium chloride -from a storage tank P. The outlet of the sludge tank is connected with a lter press Q, from which the liquid (antimony pentasulide solution) passes through a pipe R to another storage tank S. The outlet of the latter tank is connected with the up er portion of a precipitating tank "l, which a so receives sulfuric acid from a, storage tank U and compressed air through a pipe V.y rI he outlet at the bottom of the precipitating tank T is connected with a filter press W.

The solid retained by said press (filter press cake) is taken to a drier X and the dried product to a grinding apparatus Y.

In detail, the operation 1s conducted as follows: rlhe crushed nitre cake and the mev tallic antimony supplied at B and C, respeo tively, should be in such proportion as to` have about three parts (by weight) of nitre The nitre cake to one part of antimony. cake (preheated until Water has been expelled), is admitted to the furnace first, and when it is molten, the antimony and the reducing agent (coal) are added.v About part of anthracite coal will be Suitable. All these substances may he fed to the furnace together, if desired. rihe treatment of the mixture in the furnace A is continued for about from three 'to four hours, at a temperature of about 1000" centigrade, the furnace being closed by claylngf rhe reaction between metallic antimony and-the sulfuric acid contained in the nitrecake produces antimony sulfate, but the reducing atmosphere obtained by the addition of coal or its equivalent such antimony sulfate is reduced to antimony sulphide.

The reactions taking place in the furnace may be explained as follows: Nitro caire, NaHSO, may be considered as NagSQ-- H2SG4. The molecular weight of ELS@i is 98, that of hla2SO4 is 142, and that of nitre cake therefore 240, While that of antimony is 120. Therefore, if We take nitre cake and antimony in the molecular proportions of 3 to 2, tlieproportion of their Weights will be as 3 times 24@ to 2 times 126, or as 3 to l, which is the proportion 'which has been in dicated above. The reactions 1 1': v the treatment ot 3 (NazS-l-HZSQ and 28h (in the presence of carbon) are as tollows: First, there is a reaction between the sulfuric acid and the antimony,

nitre cake reacts with carbon according to the equation (e) erlasoeodnazs-peooz,

lt will be seen that nitro caire contains suluric acid and sodium sulfate in just the right proportions to produce the desired refurnace has a basic lining (bauxite),

actlons il nitre cake and antimony .are used in the proportion of 3 to l (by weight), as indicated above. lnasmuch as the relatively low temperature of about 1000 centigrade is used, there is no loss of antimony by volatilization or by decomposition, and the time required for the treatment is shorter than in methods em loyed heretofore. 'llhe and the nitre cake, (being acid in character), should not be left alone in contact with such lining for too long a time. Hence, the charge ol antimony and coal should be added soon alter the admission of the nitre cake, or even at the same time. 'lhe addition of the charge neutralizes the free acid of the nitre cake, so that there is no corrosive action on the bauxite brick,v lining. As will be understood from the equations given above, the melt, after the completion of the reaction, consists chiedy of antimony sulphide (SbzSa) and sodium sulphide (NazS). 'lhe charge is then tapped into the settler E, where 1t is cooled and broken down. 'lhe broken melt is crushed to about i; inch size or less, and b means of the elevator G, fed to the hopper and thence,with sulfur added as at d, dropped into the water contained in the disintegrator casing K 'lhe agitation produced by rotating the cylinder L causes all the soluble substances to become dissolved, steam heat or other heat'being supplied, if desired, to

presence of hasten the process of solution. Under the edect of the heat of reaction and in the the free caustic soda produced and of sodium sulphide, the sulfur becomes dissolved, probably in the form of NazS.

.The reaction between the sodium sulphide and antimony sulphide (in the presence of oxygen) may be represented by the following equation: (d) NazS-i-SbzS/s-i-O:

NaZS-l-SbzS-ihlaz.

lt is aterial whether the sulphur be added at al, as described above, or previousmeedoen it may be even be added in the furnace 'lhe sulphur is dissolved probably as NaZS in the Na formed as indicated in, equation (4;). 'lhe lumps of material tumbled about in the cylinder L break each other up by mutual attrition, until they are fine enoughto pbase through the perforations of cylinder which are enerally about f, of an inch in diameter. he solution is pumped or otherwise conveyed from fthe disintegrator t0 the slud e tank 0, where suicient calcium chloride is added (from tank P) to form a precipitate of calcium sulfate by reacting with the unreduced sodium sulfate present, and also enough to take care of the requirements for calcium sulfate later on in the process, if desired. 'lhis calcium sulfate residue (carrying with it any organic matter present), is liltered in the plate-and-frame filter press Q, and may be returned to the furnace if desired, or considered a waste material, since the amount is very small. lhe calcium chloride thus acts as a precipitant for the sodium sulfate, and also as a clarifier which efects the removal of organic material. Should the amount ol sodium sulfate present be insuiicicnt-for the removal of organic matter, a suitable additional amount of sodium -sulfate would be supplied to the sludge tank 0. The reaction between the sodium sulfate and the calcium chloride may be expressed as follows:

lt will be understood that more calcium chloride is' supplied than required by this reaction, so that the liquid leaving the lter ress Q will contain some Caille, besides the l azS and the antimony pentasuliide SbzS, in solution. ln the main, however, this liquid is a clear solution of antimony pentasulde. 'l`he resulting clear antimony pentasultide solution is conveyed through the pipe `R to the storage tank S, and is then run -slowly into the precipitating tank T con- 'lfhe reason that l add enough calcium chloride'to produce calcium sulfate is that l inlili) tend to producemthe article known in commerce as golden antimony sulphuret, which contains a certain amount of calcium sulfate. Furthermore, such golden antimony sulphuret, according to the trade specilications, is required to contain a certain proportion (from 15 to 17%) of free sulphur. As mentioned above, this sulfur, added at J or at any suitable earlier point, is dissolved in K and reaches the tank T as N azS. From this solution I precipitate sul- "fur by the action of the sulfuric acid, according to the equation I therefore obtain in tank T a mixture of three precipitates, viz; precipitates of calcium sulfate, antimony pentasulfide, and sulfur, in the proportions required to constitute the trade product known as golden antimony sulphuret. I also obtain, in addition, a gaseous product, HZS, and a solution of sodium chloride. The precipitate of sulfur, of calcium sulfate, and of antimony pentasuliide (SbgS), is separated from the liquid in the filter press W. rlhe ilter press cake is dried in the vacuum drier or other drier X a-nd then ground in the grinding apparatus Y, which may be of the impact air classiier type. Generally, the antimony sulphide (called golden antimony sulphuret in the trade), is ground to pass through a 350 mesh screen. After grinding, the product is ready for the market.

Various modifications may be made without departing from the nature ofmy invention as set forth in the appended claims.

Instead of calcium chloride, I may use barium chloride, and while the claims specii'y calcium chloride, it is to be understood that barium chloride is covered as an equivalent.

I claim: i

1. The process which consists in subjecting nitre cake and metallic antimony to a temperature of about 1000 C. in the presence of a reducing atmosphere, so as to produce antimony trisulfide and sodium sulphide, cooling and crushing the resulting melt, disintegrating it in the presence of an aqueous solvent and oxygen to obtain a so- .ution containing antimony pentasulphide,

ence of an' aqueous solvent and oxygen` to` obtain a solution containing antimony pentasulde, adding calcium chloride to the solution thus obtained separating the solu tion from the solids, bringin the separated' solution in contact with sul ic acld, and separating the liquid from the solid precipitate.

3. lThe process which consists in heating nitre cake in the presence of metallic antimony in the resence of a reducing lagent so as to ro uce antimony trisultide and sodium su phide, cooling and crushing the resulting melt and disintegrating it in the presence of sulfur and of an aqueous solvent and oxygen to obtain a solution containing antimony pentasulde, adding calcium chloride to the solution thus obtained, separat,- ing the solution from the solids, bringing the separated solution into contact with sulfurie acid, and separating the resulting precipitate from the liquid.

4. The process which consists in subjecting about three parts (by weight) of nitre cake and one part of metallic antimony to heat in a reducing atmosphere, so as to produce antimony trisulfide and sodium sulphide, cooling and crushing the resulting melt and disintegrating it in the presence of an aqueous solvent and oxygen to obtain a solution containing antimony pentasulide, addin calcium chloride to the solution thus o tained, separating the solution from the solids, bringing the separated solution into contact with sulfuric acid, and sepalxting the resulting precipitate from the li ui ntestimony whereof I have hereunto setv my hand.

GEORGE WILBUR MULLEN. 

